Note: If they all have their back to you they’re trying very hard to ignore you.

Scientists may have just found an evolutionary answer for why that idiot keeps hanging all over you at the bar without taking the hint that you’re just not that into him.

(You know the one… the one who continues to wink at you, or offer to buy you a drink, and you’re forced to make out with your husband on the spot in the hopes he’ll eventually leave you alone.)

Turns out unattractive men who are looking for a quick hookup, are more likely to overestimate how attractive women find them.

Researchers from Williams College and University of Texas at Austin took 96 men and 103 women, all undergraduates, and put them through a “speed date” type scenario. The men and women first took surveys rating themselves on attractiveness and their level of desire for a short-term sexual encounter. They then talked with five members of the opposite sex for about three minutes each. After the meeting they rated the partners on physical attractiveness and how interested in them sexually the partner appeared to be. The study will be published in the journal Psychological Science.

Researchers found men who were looking for a short-term sexual encounter were more likely to overestimate a woman’s desire for them. Men who thought they were hot also overestimated women’s desire for them. Furthermore, the more attractive the woman was to the man, the more likely he was to overestimate his desire in her.

Men who were actually considered attractive by the women’s rankings did not seem to have this discrepancy in evaluating the situation. Women, for the record, consistently underestimated their male partners’ interest in them sexually.

Researchers say there’s an evolutionary explanation for this discrepancy.

“There are two ways you can make an error as a man,” psychologist Carin Perilloux said. “Either you think, ‘Oh, wow, that woman’s really interested in me’—and it turns out she’s not. There’s some cost to that. “

But the other error a man could make is that the woman is interested and he’s missed out on a mating opportunity.